Displays of spots of light appearing to move along a straight or curved line are used for ornamental, signaling and similar purposes. A display of this type can comprise a linear array of light sources, such as lamps or light-emitting diodes (LEDs). By successively illuminating light sources along the array, a spot of light can be made to appear as though it is moving. Large displays of this type, such as those used in outdoor signage, can comprise arrays of incandescent lamps. Smaller displays of this type, comprising linear arrays of LEDs, have been used as indicators in electronic instruments and meters. Linear arrays of LEDs have also been used for ornamental and signaling purposes in electronic devices such as cellular telephones.
For example, as illustrated in FIGS. 1 and 2A-C, a moving-light display 10 disposed around the periphery of the housing of a cellular telephone 12 can comprise an array of LEDs 14, 16, 18, etc. (with others not shown for purposes of clarity). The LEDs 14, 16, 18, etc., can be covered by a translucent sheath 20 (shown partially cut away in enlarged area 22 in FIGS. 2A-C to expose LEDs 14-18 for explanatory purposes). To provide a moving-light effect, LED 14 can be momentarily turned on, i.e., illuminated, while LEDs 16 and 18 are turned off, as shown in FIG. 2A; then, LED 16 can be momentarily turned on while LEDs 14 and 18 are turned off, as shown in FIG. 2B; and then LED 18 can be momentarily turned on while LEDs 14 and 16 are turned off, as shown in FIG. 2C. Such a sequence of LED illumination provides a visual effect resembling a moving spot of light that follows the path of display 10 around the periphery of the telephone housing. Effects other than a moving spot of light can be produced by flashing the various LEDs in other patterns, such as alternately turning on the even LEDs and odd LEDs. Different display effects can be used to signal different events. For example, display 10 can provide the above-described moving-light effect to notify the user of an incoming call, and provide a flashing but fixed pattern to notify the user of a missed call or incoming text message. The display can flash in synchronism with a ringtone.
It would be desirable to provide a moving-light display that is more economical, less complex, and more readily scalable than prior displays of this type.